Control system for electric motors.



'PATENTED DEC. 10', 1907.

L. M. ASPINWALL. GONTRUL SYSTEM FOR ELECTRIC MOTORS.

APPLICATION FILED APR. 4, 1906.

2 SHEETS-SHEET 1.

WITNESSES! No. 878,284. BATENTED D50; 10, 1 907.

L. M. ASPINWALL.

CONTROL SYSTEM FOR ELECTRIC MOTORS. APPLICATION FILED APR. 4. 1906.

2 SHEETS-SHEET 2.

WM 5 v ATITORNEY low a predetermined value, in order that the motors maynot be in ured by increasing the l ouis. M. ASPI/NWALL,

that shall comprise a single limit switch and maybe adjusted at the willi such as are employed for electric railway vewhich supplies energy foroperating the acon the motor equipment at starting has been able LOprovide of Wilkinsburg, in the county of Allegheny a following is aspecification.

I in a system .hicle service, it has been found desirable and economicalto employ a system of automatic acceleration which has usually compriseda u line their operation to a predetermined sequence.

motor circuit and a. switch to be actuated l l 1 l l l consumed in"accelerating may be lrcpt'sub-.'l

s'rArs PATENT OFFICE.

or wi-citinssuae; PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE J iiiiiioraio &MANUFACTURING COMPANY, A CORPORATION or PENNSYLVANIA.

. CONTROL SYSTEM FOR ELECTRIC MOTORS.

Specification of Letters Patent. Application filed April. L 1906. SerialNo. 30%897.

No. 8713,2234. Patented Dec. 10, 1907.

T 0 all whom it may concern. cluded in series with the motor circuit atany Be it known that 1, Louis M. i isrinivnilil, one time but, sincerelatively large currents a citizen of the United States, and a residentflow through the motor circuit, 1 have provided means for adequatelycontrolling the action of the'limiting device from the auxiliarycircuits which are traversed by rela tively small currents.

and State of Pe nnsylvania, have invented new and useful Improvement inControl Systems for Electric Motors, of which the invention, thelimiting device shown therein My invention relates to control systemsfor electric motors and has special reference to such systems as embodymeans foreiiecting an automatic acceleration of the motors.

' The object of myinvention is to provide, of the class above indicated,means dependent upon predetermined value oi electric current flowing inthe motor circuit for retarding the accelerating action,

comprising a single limit auxiliary magnet winding which is opposed tothemain circuit winding and which is supplied with energy throughavariable resistance. Fig. 2 is a view, similar to Fig. 1 in which theauxiliary magnet winding for the limit switch is provided with aplurality of intermediate taps, means being provided for supplying enegy to the whole or a part of the winding at 1 he will of the attendant.

v Referring to Fig. 1, energy is supplied to an electric motor 1, from asupply line conductor 2, through a switch 3 and resistance secions a, 5and 6 to an opposite line conductor 7. The amount of resistance includedin circuit at any o e time is determined by accelerating switches 8, 9and 10 which are adapted to close automatically in a predeterminedsequence and are governed by a limit switch 11 and a master controller12. When the master controller 12 is moved from its oil position to theposition a, energy is supplied from a battery 13 through contactterminal. '14:, contact member 15, contact terminal 16 and conductor 17to an actuating magnet winding 18 oithe switch 3, circuit beingcompleted from this point through a conductor 1. to the negativeterminal of the battery. V' hen the switch 3 is closed, a circuit iscompleted from the line conductor 2 through switch 3, armature 20 andfield magnet winding .21 of the motor 1., magnet winding 22 of the limitswitch 11,- and resistance sections 4, 5 and 6 to the opposite lineconductor 7. if it is now desirable to accelerate the motor, masterswitch 12 may be moved to position b to complete the battery circuitfrom contact terminal '14 through contact terminal 23, to which it isconnected, contact member 24, contact terminal 25, conductor 26, contactterminals 27 and 28, which are connected by bridging contact member 29when the switch v of the attendant. In the operation oi variable-speedmotors,

plurality of switches so interlocked as to con VVith such anarrangement, it is. advisable to use a device tor preventing the closureof each accelerating switch until the current flowing iii themjo torcircuit ialls be.-

applied voltage too rapidly. A common form of such a device comprises amagnet coil" which is connected in series with the theveby'and adaptedtointerrupt the circuit celerating switches. Devices of this characterhavepr'oved satisfactory when the load approximately constant, as in asingle motor vehicle or in a train of vehicles each of which issuppliedwith an adequate motor equip ment, but in control systems forelectric lo-' comotives which. may be called upon to haul variable loadsthat are dependent upon the lengt and character of the train, it isdesirmeans for adjusting the pre determined current value at which. thelimit-- ing device will operate in order that'the time stantiallyconstant for all leads, *Tl'iis ra sult may be aceomplished "by'fprovidng means for varying the number of 'turns n- 1 My invention isillustrated in the accoml switch, and an 3 is closed, conductor 30,contact terminals 31 and 32, which are connected when the limit switch11 is closed, contact terminal 33, contact member 34, and contactterminal 5 35, to the actuating magnet winding 36 of the switch 8,

completed to the negative conductor 19. As soonas the switch 8 isclosed, resistance section 4 is short-circuited, and energy is 10supplied to the magnet winding 36 from conductor 37, which is connectedto contact terminal 16, through contact terminal 38 'which has now comeinto engagement with contact member 34; In this way, the initial 0eration of the switch 8 is dependent u on t e closing of the limitswitch 11 but, w en once closed, it is held in such positionirrespective of the position occupied by the limit switch, since ener toits ma 'net'winding rom the battery 13,

' throught e master controller 12.'

Since the magnet winding 22 of the limit switch 11 is connected inseries circuit with themotor .1, the switch 8 may not be closed untilthe current flowing throu h the motor circuit has decreased suificientlthe closing of the limit switch. 'When the switch 8 again occupies itsclosed position, energy is supplied, as before, through limit switch 11to contact terminal 33, which now engages a contact member 39, fromwhich point the circuit is continued through acontact terminal 40 to acontact terminal 41 of the switch 9, which corresponds to the contactterminal 33 of the switch 8, consequentlv theswitch 9 may not beclosed'until the switch 8 hasbeen closed and it is also si'milarlydependent upoIt-the closing of the limit switch 11. W en :the switch 9is closed, 40 resistance section 5 is short-circuited and energy may besupplied through the limit switch to an actuating magnet of the switch10 which, when closed, short-circuits the resistance section 6. I Whenthe load on the motor 1 is such that it is desirable to accelerate themotor more ra idly than the coil 22 of the limit switch will permit, thepull exerted by the said coil may be 0 posed to the desired degree. Asillustrate in Fig. I of the drawings, the desired regulation is effectedby means of an auxiliary magnet winding 42 which exerts a force inopposition to the force exerted by the coil 22 and is supplied withenergy from contact terminal 16 of the master switch 12, through aconductor 43, a movable contact arm 45 and a ortionor all of a variableresistance 44. included in the auxiliary winding circuit, a

minimum force opposes the pull exerted by the winding 22..v I 1 p Theenergy su pliedto the windin 42 may be. increase and the 'o posingfierce proportionately strengthened, the active length of the res stance44 which are connected to the end from which point circuit is y isapplied directly y to permit- 'the contact bearing member 54 and themov- 'hen all the resistance 44 is tent-1y energize the y decreasingthrough the coiiperation of the contact arm- 45 and a series of contactterminals 46,

and intermediate oints of the resistance.

Since tlie action'of the limit switch depends upon both the winding 22and the winding 42, its operation may be varied by varying the ampereturns of themagnet winding 42 in any practicable manner.

eferring to Fig. 2, which illustrates a simi- '75 lar system to thatofFig. '1, the limitingswitch 11 is provided with an auxiliary magnetwinding 47 which corresponds to the winding 42 of Fig. 1, the ampereturns of the winding being varied in this case by adjusting the numberof convolutions includedin the circuit at any time, which adjustment iseffected by a device 48. The device 48 comprises electro-magnets 49 and50 having movable core members 51 and 52, a ratchet member 53, a movablecontact-bearing member 54 and engaging fingers 55, 56, 57 and 58. Theratchet member 53 and the contact member 54 are attached to o positeextremities of a connecting rod 59 w iich extends throu h a hole in themovable core member 52 o the electro-magnet 50 in which it is free tooperate. The ratchet member may be enga ed by a pawl 60 which ispivotally connecte to the movable core member 51 of the electro- 95magnet 49, and by a stationary pawl 61. When the electro-magnet 49 isdeenergized the core member 51 oc'cupi's its lowest position and aspring 62 is interposed between able core member 52 of theelectro-magnet 50 in order to force the rod and the core member inopposite directions and normally hold the latter at the upperexlremityof its path ofmovement. The upper end of the movable 10! coremember 52 is beveled and when the electro-magnet 50 is deenergized, thebeveled edge moves the pawls 60 and 61 out of engagement with theratchet member 53. The ratchet member is )rovided withnotches 64, 65, 66and 67 an the arrangement of the parts is such that when current issupplied to electro-magnet 50 and electro-magnet- 49 is denergized, bothpawls engage the notch 64 and the contact finger 55 engages a contactmember 68. If the electro-magnet 49 is then energized, the core member51 is moved'to its uppermost position, against the force ofgrav- .ity,and the ratchet member 53, the connecting rod 59 and the movable contactmember 54 are moved by the pawl 60 until the stationary pawl 61 engagesthe notch 65. In a similar manner, by continuing tointermitelectro-magnet 49. the stationary pawl fil'success vely engagesthe notches 66 and 67 and the movable contact member 54 is movedsuccessively into engagement with contact fingers 57 and 58.

' f the electro-magnet 50 is denergized at any stage of the operation,the ratchet mem- 1'80 ber 53 is immediately released from the pawls 60and 61 by the movable core member "52 and the contact member 54 isreturned to its "f initialposition by theaction of the spring 59.

5 The Intermittent energizing of, the electromagnet 49'ma beefl'ected bythe operation of a-siinple ma e and break switch 69 and the energizingof the 'electro-magnet 50 is depen upon the master switch 12 so that,

themovable member54' is returned to its 'moved to its o position. Thecontact fingers 55-, 56, 5 7 and 58 are connected toone extremity and tointermediate points of the 15. 1 this winding is connected to thenegative batwinding 47 and the opposite extremity of teryterminalthrough conductor 19. The

contact finger55 is connected to thesupply.

conductor17 and is adaptedtocontinuously engage the contactmember (SS-asthe latter moves into enga pawls 60and 61 u n the notches 64, 65, 66and.67 of, the ratc et member 53.

contact member .54 occupies its initial posi;

apart-or thewhole o 'thewindingfl In n will be noted that ad'us'tinentin the effected by varyin the. number of convolu- "tions included in thecircuit whereas ad ustment of the m etic force exerted by the the amountof current flowing through the coil by means of a resistance in'seriestherewith. The latter; method. is advantageous for the reasonthatasing'le supply conductor 45 the former :metl o'd is advantageous isnecessary .for the auxiliary winding while or the reason that no currentis supplied to' the auxiliary. winding under normal operating conditions"and for the further reason that 50 the. device is automaticallyreturned to its initial positionwhen the master switch is re'- turned-toits off position.

Although the systemsillustrated comprise single motors and controlsystems therefor, my invention is not restricted to such arranements'but may andprobably will be app ed to railway vehicle equipmentsin which several motors are employed.

I claim as my invention:

to f 1. The combination with a plurality of motor-controlling switchesthat are adapted initial position when the master switch is ement withfingers 56, 57 v and 58 successively through the action of the 'Itwillbe observed that when the movable winding. 42 of Fig. -1 is effectedbypvarying' to close in a predetermined sequence, a inaster contrclierand a limit switch for retarding the operat on of said motor controllinswitches, of an independently controlle means for regulating the actionof said limit switch. v

, 2. The combination-with a plurality of motor-controlling switches thatare adapted to close 1n a predetermined se uence, a inaster controllerand a limit switc for retarding the operation of said motor-controllingswitches, anopposmg magnet coil for said limit switch, and "meansindependent of the master controller for turns in said coil.

3. The combination with a plurality of motor-controlling switches thatare adapted v rarying the ampere.

to close in a predeterminedsequence, a master controller and a limitswitch for retarding the operation of said motor-controlling. switches,an opposing magnet coil for said limit switch, a resistance in series'circuit therewith, and an independently operated switch for varying thesaid resistance.

'4. The combination with an electric motor, resistance sections inseries therewith,

short-circuiting switches for said resistance sections that are adaptedto close in a predetermined sequence, a master controller and 'a singlelimit switch, of means for adjusting theoperation of the llll'llll}switch, said means comprising a switch'the operation of which isindependent of the niaster controller.

5. The combination with an electric motor, resistance sections in seriescircuit therewith, switches that are adapted to short-circuit" theresistance sections, a limiting switch which is dependent for its actionupon the current flowing in the motor circuit, and a master controller,of an auxiliary magnet coil and means for varying the ampere turns ofsaid coil, said means comprising an independently operated switch.

6. The combination with an: electric motor, resistance sections incircuit therewith, short-circuit-ing switches therefor which are adaptedtoclose in a predetermined sequence, a master controller, and a limitswitch'having an operating coil connected in series with the motorcircuit, of an. auxiliary magnet coil which is opposed to the maincircuit coil, and means for varyin the ampere turns in the auxiliarycoil,.sai means comprising an in 'deplendently operated switch.

testimony whereof, I have hereunto subscribed my name this 30th day oiMarch,

1906. LOUIS M. ASPINWVALL.

Witnesses:

H. A. MULLETT, I -BIRNEY' Hines;

